I had this problem once, during the Black Friday sale. I had to make another account and gift the game to myself from there. The problems is related to your account, not the card, if it's the same one I had. It should go away by itself in a couple of days.

@d37r17u5
mine didnt fail immediately its more like [working...] for a few seconds and pop up the message declined... now i feel less worried. I just sad that i couldnt start swinging like spiderman in justcause, i tried the demo it was pretty awesome *sadface

Most likely Valve's overzealous fraud protection has kicked in. This has been happening a lot lately, even when there are no problems with your cards. All you can do is to contact support and have them reset your account.